# Tag Info

## New answers tagged plasma-physics

2

It actually turns out that the number density is an important aspect of defining a plasma. The general definition is a plasma is a quasi-neutral gas of charged and neutral particles which exhibit collective motions The three conditions for exhibiting collective motions is temperature and (number) density dependent, stemming from the Saha equation, are ...

3

In the old days, most plasmas were created with discharges in gases or such. This can stay a plasma for a long time (at least seconds). If it were not quasi-neutral, the accumulated charge would strongly pull ions away from electrons and make the plasmas explode. That's why books make this claim, and it is still true in many cases. Nowadays, plasmas can be ...

1

In a plasma it is hard to specify the state as solid, liquid, or gas but a good way to think about it is to ask what is driving the interactions in the plasma. Literature often cites the plasma coupling parameter $\Gamma=Z^2 e^2/(k_b T a)$ where a is proportional to $(number \ density)^{-1/3}$, T is the temperature, and Z is the charge number. This can ...

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